I'll post the old one I had this weekend; it is good enough for sublime stuff. The newer one is more solid, but I don't have it complete enough to really be useful. I'll be honest though, I don't think the YAML tmLanguage will ever be perfect. It is such a hard language to highlight well with regex, but it will certainly be better than the default one.
Anyways, I don't know when the new one will be done. I have to motivate myself to keep working on it , but I will post the current iteration I use for Sublime stuff.
Keep an eye out for FichteFoll's project as well. I know he has taken it upon himself to produce a definitive package for working with YAML|PLIST|JSON. I don't know how far out his project is, but maybe he will have the motivation and time to take his to a higher level.
I still have a couple of things I want to workout on this package in the conversion area; I keep flip flopping on how I want to handle some things.